Because Dec. 26 falls on a Monday, store traffic could be up as much as 60% over the same date last year, which was a Sunday, according to ShopperTrak, a research firm that monitors traffic at more than 25,000 stores.

Shoppers should expect to see big after-Christmas sales, early hours and some Black Friday-type door-buster deals designed to draw people into stores, according to retail experts.

This Christmas was a little brighter for the nation’s retailers, with holiday sales up 3.8 percent over a year earlier, according to the national retail federation.

Consumer experts said final sales figures for the two month period are expected to hit $469 billion nationwide, but analysts caution that sales were driven by heavy discounting.

“Mega Monday” isn’t only about post-holiday sales. It also will likely be the biggest day for returns and exchanges.

Retailers estimate that holiday returns will total a record $46.3 billion this year, up 4% from last year and 10% from two years ago.

Consumer experts said many stores that are looking to keep customers and entice them to make future purchase are lightening up on their return policies. For example, consumers may find longer return periods, fewer retailers requiring receipts and fewer stores charging fees for electronics that have been taken out of their original packaging.

Still, consumers shouldn’t wait too long. Some items — especially electronics — have a shorter return window. Target, for example, has shortened its return time for tablets, netbooks, e-readers, cameras and camcorders to 45 days, down from 90 days last year. A company spokesman said the new deadlines are clearly noted on store shelves and receipts.

Also, shoppers who return gifts without receipts or other proof of payment may end up receiving the current selling price of the item, which may be lower than what was paid. In other cases, the retailer may decline the return all together.